This invention is directed to silicone compounds, and methods of making silicate-based sheet and tube type siloxane polymers.
Silicones are made from silica by reducing it in an electric furnace to elemental silicon, i.e., EQU SiO.sub.2 +2C.fwdarw.Si+2CO
The elemental silicon is treated with RC1, typically methyl chloride, in the "Direct Process", as the basis of commercial production, i.e., EQU Si+2RCl.fwdarw.R.sub.2 SiCl.sub.2
Hydrolysis of the organochlorosilanes gives siloxane structures which are used in the manufacture of many silicone products, i.e., EQU nMe.sub.2 SiCl.sub.2 +2nH.sub.2 O.fwdarw.nMe.sub.2 Si (OH).sub.2 +2nHCl EQU n[Me.sub.2 Si(OH).sub.2 ].fwdarw.HO(Me.sub.2 SiO).sub.n H+(n-1)H.sub.2 O
Alternative routes to silicones involving the preparation of silicone pollers from silicate materials are embodied in U.S. Pat. No. 3.661,846 (May 9, 1972). The copending U.S. application Ser. No. 08/542,081, is an improvement and furtherance of the efforts described in the '846 patent to find other unique approaches in the manufacture of silicones. This present invention is a modification of the process generally described in the '081 application.
Thus, according to the '081 application, sheet or tube silicates are reacted with an alkenyl group containing chlorosilane to produce an alkenylsiloxy polymer. The alkenylsiloxy polymer is then further reacted with a hydrosilane in the presence of a platinum catalyst to produce an organopolysiloxane polymer.
In this present invention, however, sheet or tube silicates are reacted with an organo-H-chlorosilane to produce an organosiloxane polymer with pendent .tbd.Si--H groups. The organosiloxane polymer with pendent .tbd.Si--H groups is then further reacted with an olefin in the presence of a platinum catalyst to produce the organopolysiloxane polymer.
In the '081 application, four of the four reactants contain the silicon atom. In the present invention, only three of the four reactants contain the silicon atom.
Thus, the term hydrosilation applies to the addition of Si--H across any unsaturated species, i.e. EQU .tbd.SiH+CH.sub.2 .dbd.CH(R).sub.n Si.tbd..fwdarw..tbd.Si--CH.sub.2 CH.sub.2 --R.sub.n --Si.tbd. (I)
or EQU .tbd.SiH+CH.sub.2 .dbd.CHR.fwdarw..tbd.Si--CH.sub.2 CH.sub.2 --R(II).
Silanes and siloxanes that contain a silicon bound hydrogen atom can add across the double bond. Typically, these reactions are conducted in the presence of a platinum catalyst or a catalyst which is a complex of platinum. Scenario (I) corresponds generally to the process in the '081 application, whereas Scenario (II) corresponds generally to the process in the present invention.